| As the device dimension continuous shrinking in ultralarge-scale integrated circuits (ULSI), the resistance-capacitance (RC) delay of interconnects becomes a major problem, which leads to signal propagation delay, dissipation and cross-link between metal interconnects. In order to address the problems, the Al/SiO2 structure must be replaced with low dielectric constant materials and low resistivity metal interconnects. As the substitution of SiO2, the porous low dielectric constant (low-k) and ultra-low dielectric constant (ultralow-k, k < 2) materials have received more close attention recently.The etching of porous low-k materials is a key step in the ULSI fabrication. Due to the existing of pores in the SiCOH film, the etching rate of films can increase with reduced film density, resulting in roughness, the formation of micro-trenches, and variations in the etched depth, which make the precise profile control of etched patterns uncontrollable in the etching process. For the etching of SiCOH films, fluorine atoms are found to be the efficient etching agents. However, the interaction between fluorine atoms and SiCOH films and the deposition of CF films will have influence on the properties of Cu/SiCOH system and the structure of SiCOH films.This paper investigates the characteristics of SiCOH low dielectric constant films treated by CHF3 electron cyclotron resonance plasma. By capacitance–voltage, current-voltage and water contact angle measurement, and FTIR and AFM analysis on the bonding configuration and microstructure, it is found that the CHF3 plasma surface treatment of SiCOH films can lead to the small shift of flatband voltage VFB, the decrease of leakage current and the decrease of surface roughness, but the poor hydrophobic property. |
